1. Field of the Invention
The present general inventive concept relates to a hard disk drive, and more particularly, to a shape of a surface of a head slider that faces a disk.
2. Description of the Related Art
Hard disk drives (HDDS) are auxiliary memory devices used in computers, MP3 players, and mobile phones to read data recorded on a disk using a magnetic head or to record new data on the disk. The magnetic head is formed on a head slider that is mounted on a front edge portion of an actuator in the HDD. The disk is mounted and rotated on a spindle motor, and the head slider is moved to a certain track on the disk by the actuator while floating at a predetermined height above the rotating disk. The magnetic head formed on the head slider records data on the certain track, or reads data recorded on the certain track.
In a normal operating status of the HDD, the floating height of the head slider is determined to be a height where an upward force of the head slider by air flowing through a disk facing surface of the head slider balances with an elastic force of a suspension in the actuator that supports the head slider. The upward force of the head slider is largely affected by changes of physical property of the air flowing through the disk facing surface of the head slider.
Recently, host systems, such as MP3 players and mobile phones, including the HDDs can be portable, and thus may be used in regions of high altitudes, for example, in mountains or planes. However, a density of air in highlands is lower than that of lowlands, and thus an atmospheric pressure is lowered and a molecular mean free path of air, that is, a distance over which a molecule of air can fly without colliding with other molecules, increases. In addition, when the altitude increases, a temperature of the atmosphere is lowered, and a viscosity thereof is reduced. The above changes of physical properties of the air reduce the upward force of the head slider.
FIG. 1 is a graph illustrating a result of a simulation using a conventional head slider. The graph of FIG. 1 illustrates a relationship between a floating height of the head slider and altitude in the conventional HDD.
Referring to FIG. 1, when the altitude becomes higher from a sea level altitude 0 kft to a sea level altitude 20 kft, the floating height of the head slider becomes lower. The decrease of the floating height of the head slider in highlands increases a possibility of collision between the head slider and a disk of the conventional HDD. Then, the head slider and the disk may be damaged due to such a collision, and a reliability of a performance of the conventional HDD may be degraded.